Rotor equipped aerial device



April 27, 1948.

RF. PITCAIRN 2,440,291

vROTOR EQUIPPED AERIAL DEVICE Filed May 5, 1944 3 Sheets-Sheet 1 2 5 .H IN VENTOR ARow P/TCA/AN E g M? A TTORNEY April 27, 1948. H. F. PITCAIRN 2,440,291

ROTOR EQUIPPED AERIAL DEVICE Filed May 5, 1944 3 Sheets-Sheet 2 W INVENTOR HAROL EP/rcA/R/v BY ATTORNEYJ April 27, 1948. PlTCAlRN 2,440,291

ROTOR EQUIPPED AERIAL DEVICE Filed May 5, 1944 3 Sheets-Sheet 3 INVENTOR HAROLD. E P/TcA/R/v 1 ATTORNEYJ Patented Apr. 27, 1948 Harold Pitcairn,

Bryn Athyn, 2a., assignor to Autogiro .Company of America, *Philadelphia, Pa, a corporationof Delaware Application May 5, 1944, Serial No. 534,245 (01. 244-138) 311 Claims.

This invention relates to aerial devices and-is particularly concerned with an aerial device equipped with a bladed rotor, the device being adapted to be released or launched at anelevation, for instance from an airplane, whereupon the rotor serves to provide retarded descent of the device to the ground.

Various features of the invention are adaptable for a number of purposes. For example, the de- Vice may be employed as an aerial bomb, for instance a high explosive bomb. Alternatively the device may take a form suitable for the safe dropping of cargo, or even of an occupant.

One of the o-bjectsof the invention is the provision, in devices of the type mentioned, of a rotorcompris-inga single counterweighted blade mounted and arranged to provide for compact stowage of a plurality of similar devices. Alternatively the rotor may incorporate a plurality of blades which are arranged to provide fori'olding so as to permit compact stowage. In either of these alternatives, it is contemplated that a plurality .of the devices, for instance, explosive bombs, may be stowed by stacking the devices adjacent each other, with the several devices serially offset lengthwise thereof and with the rotor-end of one device nested in the corner formed between the-body blades of an adjacent device.

In an embodiment incorporating a single counterweighted blade, the. invention includes a novel form of rotor mounting yoke to which the single blade and counterweight are pivotally attached, soxthat theblade may pivot or swing todifferent positions one of which is-adapted to the compact stowage above mentioned.

Preferably the rotor mounting yoke is rotatively connected with the body portion of the device, and yielding means reacting between the blade and the yoke are provided for the purpose of restraining certain movementsoi the blade on its pivot. The invention contemplates a yielding blade movement control device, such as a spring, which acts to retain the blade in a position in which the longitudinal blade axis lies approximately perpendicular to the rotational axis, for convenience in stowage, the spring further servingito restrain the'blade as against excessive upward swinging movement and thereby aid in holding the blade in an appropriate :position for initiation of rotation of the rotor at the time the device is launched.

Accordingto the invention, the rotor mounting yoke is also desirably dimensioned to permit swinging of the counterweight therethrough for portion and-the blade or 2. the purposeof avoiding shocks to the rotoror its mounting at the time-the device is launched.

In an embodimentincorporating a plurality of blades, for instance a pair of oppositely-disposed blades, the invention contemplates the employment of pivot devices for the blades arranged to permit folding of one blade over the top-of the rotor to a position substantially paralleling the opposite blade, this folding also serving to facilitate stowage of a plurality of devices in the general manner above referred to.

In accordance with another aspect of the invention, provision is made for control of the path of descent-of the-device. Preferably controllable means is provided, the controllable means being operative ina pluralityoi senses. In thecase of adev-iee arranged .to carry an occupant, the y controllable means may be manually aotuated by the occupant. On the other hand, the flight-control means of-any form of device whether man-carrying or not, may be actuated by remote control means, for instance by'known typesof radio re mote control equipment.

In one advantageous form, the controllable means comprises a pair of oppositely disposed fins, together with means for differentially or similarly varying the angle of the fins to the flight path. A simple control system is thereby provided which .isneffective :to influence the. angle of descent and also the position-of the .body portion about a generally vertical axis.

How the foregoing objects and advantages are attained, together with others-which will occurte those-skilled inrthe art will be apparent from the following description referring totheaccompanyingdrawings in which- Figure 1 is an eievati-onal view of oneembodiment equipped with a single counterweighted rotor blade;

Figure 2 is a view partly'in elevation and partly in vertical section, the view being taken at-right angles to Figure 1;

Figures is a view of the rotor mounting-and control mechanism, partly in section, the sectional-partof this view being taken as indicated by-the line 3-3 on Figure 2;

Figure 4 is a top plan view of the device of Figures 1 to 3;

Figure 5 is aside view partly in vertical section of another embodiment ofthe device incorporating a 2 bladed rotor;

Figure-6 is a top plan view of 'thedevice of Figure 5;

Figure '7 i'sa view of a plurality of devices of the type shown in Figures 5 and 6, the devices being stacked for compact stowage, for example, in the bomb bay of an aircraft, as described hereinafter; and

Figure 8 is another view of the stacked arrangement shown in Figure '7, this view being taken at right angles to Figure '7.

For purposes of the following description, it is assumed that the device illustrated in Figures 1 to 4 comprises an aerial bomb of the explosive type. The body or bomb shell I is provided at its upper end with a generally cylindrical rotor supporting casing I I in which the rotor supporting yoke I2 is rotatively mounted by a bearing I3.

A single rotor blade I4 and its counterweight the unit being piv- I5 are formed as a rigid unit, otally connected by means of a pivot It in the upper open end of the yoke I2. vides freedom for swinging movement of the blade in a direction transverse its mean rotative path of travel and a bias spring II normally acts to restrain the blade from excessive upward swinging movement above the meanpath of rotation. Preferably the axis of pivot I6 is oblique to the longitudinal axis of the blade, the obliquity being such that, when viewed in plan, the pivot axis makes an acute angle with the blade axis at the leading side of the blade axis and the outboard side of the pivot axis. This causes the pitch angle of the blade to decrease as the blade swings upwardly and thereby provides for initiation of rotation of the rotor when the device is launched. The obliquity of the pivot I6 should be such that a negative angle is attained upon substantial upward swinging movement of the blade, to ensure initiation of rotation. In some cases a considerably larger angle may be needed than that shown in the drawings, the showing in the drawings not being intended to indicate any exact value.

As clearly seen in Figure 2, the yoke I2 is confiured to accommodate the counterweight I5 even permitting the counterweight to swing through the yoke, for instance when the blade takes the position indicated in dotted lines at Me in Figure I 2. This feature is of importance at the time of launching or releasing the device, for reasons brought out just below, 7

Although the device may be equipped with rotor drive means, in the preferred construction it is contemplated that the rotor blade be arranged to be wind-driven or aerodynamically T0",

tated during descent of the device to thereby provide for retarded descent. Since the rotor is not turning at the moment of launching, the air striking the blade will cause the blade to swing to a high coning angle when the device is first re-,

leased. The air flow across the blade, however, will initiate rotation thereof and as the rotational speed picks up, the blade will assume a position more nearly perpendicular to the axis of rotation under the influence of centrifugal force. The provision of the mounting yoke for the rotor, through which the counterweight may freely swing avoids shocks to the device at the time of launching. It may here be further noted that the bias spring I'I will aid in bringing the blade to an appropriate position for initiation of rotation, and thereby avoid the possibiltiy of unretarded descent of the device with the blade in the position indicated at hid in Figure 2. The spring II, however, should not be under tension when the blade is in the average coned position during descent of the device.

A stabilizing fin 2!] is desirably positioned at one side of the rotor mount I I, this fin serving to Pivot it procontribute weathercoc stability in the path of descent. As seen in Figures 1 and 3, the rotor is also advantageously mounted with its rotational axis offset somewhat from the center of gravity of the body portion, the efiect of which is to cause the device to drift (toward the left as viewed in Figures 1 and 3), even in situations where the device is launched from an aircraft not in translational motion at the time of launching. This offset of the rotor axis and the weatheroock action of the fin 20 cooperate in automatically providing an inclined path of descent, such as indicated by the arrow D, and in retaining the body portion in a given position about its vertical axis.

In the embodiment of Figures 1 to 4, the features referred to above are further employed in combination with controllable means for regulating the path of descent of the device. This controllable means comprises a pair of oppositely disposed fins 2I-2I arranged in vertical planes at right angles to fin 20, each fin 2| being mounted on a shaft 22 carrying an arm 23 which is connected by a link 24 with an arm 25, the two arms 25 in turn being coupled with the control lever 26. The control lever is mounted on pivots 21 and 28 extended at right angles to each other and providing for universal movement of the lever 25. With this system of controls and with appropriate flexible joints at the upper and lower ends of links 24, movement of the control lever in the plane of the general flight path, i. e., to the right or left as viewed in Figure 3, effects conjoint tilting of the two fins 2| in the same sense. On the other hand, when viewed as in Figure 2, movement of the control lever 26 to the right or left effects differential movement of the two fins 2 I2 I,

The foregoing control system may be manually operated in a device adapted to carry an occupant or, alternatively, in any form of device the control lever 26 may be coupled with remote radio control equipment which, if desired, may also be housed within the rotor mount I I.

According to the foregoing the flight path of the device may be controlled in two senses. Thus when the fins 2I--2I are concurrently moved in the same sense, the inclination of the flight path is varied. On the other hand, differential movement of fins 2I-2I' may b employed to change the direction of the flight path. In this way a high degree of accuracy, within a reasonable range of angles of descent, is attainable, so that, in the event of a remotely controlled explosive bomb, even a, small target may be bombed with great accuracy.

In considering the operation of the device, especially when it takes the form of a remotely controlled bomb, it may be mentioned that the rate of descent will depend upon various of the rotor characteristics, such as rotor blade pitch angle, blade length, etc. Where relatively high speed descent is desirable, for instance, for the purpose of maintaining sufficient velocity to effect at least a resonable degree of penetration upon impact, it may be of advantage to employ a blade of rather small radius, such as indicated in Figure 2. With respect to the blade pitch .angle to be employed, it may be said that appreciable variation is permissible. An appropriateautorotative setting found suitable for the purpose is about 4 or 5 degrees above the no-lift setting calculated with reference to a plane perpendicular ano es-r:

rotor; equippedi shall; be:

the'path ofdescenti In this way, or otherr operator of: the remote control mechanism': for: the bomb will be enabled I to strike even arelatively smal-li specific target with great accuracy-. descent in the oaseof a rem'otely controlled bomb benot-retarded appreciably more than required" for purposes of directional control, in order to retain"at-least-somepenetrating power at the time of impact.

In the embodiment ofFigur'es 5 and 6, the body portion is. indicated at' BiF and th'e hollow rotor mount at 3|, which rotor moun't'may also carry a fixed fin 32-as in Figures l-to 4.

In this second embodiment, the rotor incorporates aLp'air of blades 33-33 connected by a flapping pivot B l-with a-linl z 35, the-two lin'ks 35-beingconnected in common by another pivot- Sdwith-the rotati-ve hub member 31; Pivot fi'fi isdesirably oblique to the axes of the blades for reasons discussed above inconnection with'Figures" l-to A bearing 38 serves to mount the'hub foprotation'ina ring 39 which ring-ispivotallymounted-ih another ring to by means of trunnions, oneof which is indicated at 41: Rin'g' lil"; inturn; is carried by'trunnions E2 in apertured' lugs 43' projecting'from the top of the rotor mount '3 I. The rotor hub is thus mounted with freedom for tilting movement in all directions andthis tiltingmovementiis controllable byfmeans of. lever 39a which is connectedwith the innerrihg 39"ofthe mounting assembly,

In this form of device, therefore, controlin all directions is obtainable by inclination of the control lever 39a, which may either be manually actuated or actuated by remote control mecha nism. The fixed stabilizing fin 32 cooperateswith the rotor control system in providing the desired fiight .path and in maintaining the desired orientation of the body portion in the flight path.

The blade mounting pivots 34 and 36 not only provide freedom for swinging movements of the blades under the influence of various forces encountered in the descent of the device, but in addition these pivots provide for folding of one of the blades to a position overlying the other, as shown in dotted lines at 33a in Figure 5. The importance of this, particularly in an aerial bomb, will appear more fully from description below of the preferred method of stowing the devices, as illustrated in Figures 7 and 8.

In considering Figures 7 and 8 it is first noted that the stowing method shown therein is especially adapted to rotor equipped aerial bombs. Moreover, while the devices shown in Figures '7 and 8 are of the type illustrated in Figures 5 and 6, nevertheless the same pattern and method of stowage may be adapted in connection with devices of the type illustrated in Figures 1 to 4.

In Figures '7 and 8 a fragmentary sectional illustration of the shell of an aircraft appears at 44. This shell has a suitable bomb bay door 44a provided below the region in which the devices are stowed in the aircraft.

It will be seen that the general pattern of stowing contemplates arrangement of the devices in one or more vertical groups, which groups, because of the arrangement and mounting of the rotor blades 33 and of the stabilizing fins 32 may be brought quite close to each other, thereby effectively utilizing the available stowage space,

explosive bomb, that th'e rotor arranged to. retard i the rate" of: descent justi sufficiently to ermit the desired control of the bombardier It? is advantageous that the rate of each of which is an'd superimposed one above the other, the devices*being'seriallyoffsetlengthwise of the body portions inpositions so that the rotor-endof an upper device is nested in the corner formed between the body and blades of a lowerdevice. In

staclrihg thedevices may also be turned so as to bring the stabilizing fins toward one side, thereby enabling stackingin compact formation. The racks for holding and releasing the bombs are not illustrated'since they formno part of'the in- 1 vention.

Although-the pattern of the groups or stacks might be inverted, with the rotor blades extende'd downwardly from each device instead of upwardly'aseshownin Figures 7 and 8, the upward extension ofthe rotor blades is of advantage for the reason that when the devices are released, less tendency is set up for the blades to whip around during the initial portion of the descent prior tothe time rotation of the rotor blades is established.

1'. Anaerial device, adapted to be'released from an aircraft in flight, comprising a body portion and" a bladed rotor adapted to provide for ret-tarded descent of the device, the rotor being mounted on the body portion with its axisolfset from thecenter of gravity of the body portion in such manner as to ensure descent of the device'in an inclined path.

22 construction according to claim 1 whereiii-said body portion is elongatedand the rotor axisisapproximately parallel with the long axis of said body portion but offset therefrom and thus from the center of gravity.

3. A construction in accordance with claim 1 and further including a stabilizing fin mounted on the body portion and offset in the direction toward which the rotor axis is offset.

4. A construction according to claim 1 and further including controllable means for regulating the path of descent.

5. An aerial device adapted to be ejected from an aircraft in fiight comprising a body portion, a bladed rotor rotatively mounted on said body portion to provide for retarded descent of the device, and a pair of oppositely disposed differentially movable fins mounted on said body portion and providing for control of the device during its descent, and further including co-ordinated means for adjusting said fins in the same sense and differentially.

6.'An aerial device comprising an elongated body portion and a rotor comprising a single counterweighted blade disposed at an end of the body portion and providing for retarded descent of the device with the rotor uppermost, together with rotor mounting means including a blade pivot providing for swinging movement of the blade between a position in which the longitudinal blade axis is normal to the longitudinal body axis and a position in which the blade trails the body portion in a root-first attitude and in which said blade and body axes are substantially coincident.

7. A construction in accordance with claim 6 in which the rotor mounting means extends upwardly, and the lower end thereof is rotatively journalled on the body portion.

8. An aerial device comprising an elongated body portion and a rotor comprising a single counter-weighted blade to retard the descent thereof in an endwise position, the blade and counterweight being pivotally mounted at an end of the body portion to provide freedom for swinging movement thereof during normal operation in a direction transverse the mean rotative path of travel of the blade, and in which the blade is biased to oppose extensive upward swinging movement of the blade.

9. An aerial device comprising an elongated body portion and a rotor comprising a single counter-weighted blade to retard the descent thereof in an endwise position, the blade and counterweight being pivotally mounted at an end of the body portion to provide freedom for swinging movement thereof during normal operation in a direction transverse the mean rotative path of travel of the blade, and the device further including bias means normally tending to restrain extensive upward swinging movement of the blade, the blade, counterweight, blade pivot means and bias means being mounted to rotate together with respect to the body portion.

10. An aerial device comprising a body portion, a rotor comprising a single counterweighted blade providing for retarded descent of the device, rotor mounting means including a pivot providing for blade swinging movement between one position in which the blade extends generally perpendicular to the axis of rotation and a second position in which the blade axis approximately coincides with the axis of rotation, and yielding means acting to restrain the blade against excessive upward swinging movement.

11. An aerial device comprising a body portion, a rotor comprising a single counterweighted blade providing for retarded descent of the device, rotor mounting means including a pivot providing 10r blade swinging movement in a plane substantially perpendicular to the plane of rotation through a range extending upward from a position perpendicular to the axis of rotation to a position substantially beyond that in which the longitudinal blade axis and the axis of rotation are coincident, and means operative in the upper portion of such range urging the blade toward that part of the range between the coincident position and the perpendicular position.

HAROLD F. PITCAIRN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 1,964,016 1,537,713 1,799,664 1,880,586 1,673,233 1,804,869 2,044,819 1,345,159 1,811,867 2,054,355 1,799,664

Number Name Date Wiley June 26, 1934 Sperry May 12, 1925 Williams Apr. 7, 1931 Tiling Oct. 4, 1932 Cierva June 12, 1928 Gambarini May 12, 1931 Taylor June 23, 1936 Freeman June 29, 1930 Serragli June 30, 1931 Anderson Sept. 15, 1936 Williams Apr. 7, 1931 FOREIGN PATENTS Country Date Great Britain May 2, 1939 Great Britain Mar. 1, 1937 Germany June 2, 1938 

